/*
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 *    Splitter.java
 *    Copyright (C) 2001 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.classifiers.trees.adtree;

import weka.core.Instance;
import weka.core.Instances;
import weka.core.RevisionHandler;

import java.io.Serializable;

/**
 * Abstract class representing a splitter node in an alternating tree.
 * 
 * @author Richard Kirkby (rkirkby@cs.waikato.ac.nz)
 * @version $Revision: 1.5 $
 */
public abstract class Splitter implements Serializable, Cloneable,
		RevisionHandler {

	/** for serialization */
	private static final long serialVersionUID = 8190449848490055L;

	/** The number this node was in the order of nodes added to the tree */
	public int orderAdded;

	/**
	 * Gets the number of branches of the split.
	 * 
	 * @return the number of branches
	 */
	public abstract int getNumOfBranches();

	/**
	 * Gets the index of the branch that an instance applies to. Returns -1 if
	 * no branches apply.
	 * 
	 * @param i
	 *            the instance
	 * @return the branch index
	 */
	public abstract int branchInstanceGoesDown(Instance i);

	/**
	 * Gets the subset of instances that apply to a particluar branch of the
	 * split. If the branch index is -1, the subset will consist of those
	 * instances that don't apply to any branch.
	 * 
	 * @param branch
	 *            the index of the branch
	 * @param sourceInstances
	 *            the instances from which to find the subset
	 * @return the set of instances that apply
	 */
	public abstract ReferenceInstances instancesDownBranch(int branch,
			Instances sourceInstances);

	/**
	 * Gets the string describing the attributes the split depends on. i.e. the
	 * left hand side of the description of the split.
	 * 
	 * @param dataset
	 *            the dataset that the split is based on
	 * @return a string describing the attributes
	 */
	public abstract String attributeString(Instances dataset);

	/**
	 * Gets the string describing the comparision the split depends on for a
	 * particular branch. i.e. the right hand side of the description of the
	 * split.
	 * 
	 * @param branchNum
	 *            the branch of the split
	 * @param dataset
	 *            the dataset that the split is based on
	 * @return a string describing the comparison
	 */
	public abstract String comparisonString(int branchNum, Instances dataset);

	/**
	 * Tests whether two splitters are equivalent.
	 * 
	 * @param compare
	 *            the splitter to compare with
	 * @return whether or not they match
	 */
	public abstract boolean equalTo(Splitter compare);

	/**
	 * Sets the child for a branch of the split.
	 * 
	 * @param branchNum
	 *            the branch to set the child for
	 * @param childPredictor
	 *            the new child
	 */
	public abstract void setChildForBranch(int branchNum,
			PredictionNode childPredictor);

	/**
	 * Gets the child for a branch of the split.
	 * 
	 * @param branchNum
	 *            the branch to get the child for
	 * @return the child
	 */
	public abstract PredictionNode getChildForBranch(int branchNum);

	/**
	 * Clones this node. Performs a deep copy, recursing through the tree.
	 * 
	 * @return a clone
	 */
	public abstract Object clone();
}
